The OntoSelect Library provides a catalog of ontologies ranging from cars to plants. There are search and browse functions provided for users and the library tracks metadata for ontologies, including format, language, and domain.

Marine Metadata Interoperability (MMI) is an organizacion which mission is promote the exchange, integration and use of marine data through enhanced data publishing, discovery, documentation and accessibility.

Its web offers some 'MMI Guides' to help researchers and data managers follow best practices in metadata development, interoperation, and distribution, and to foster community involvement in this process. In this context, they have a section of a guide that covers methods for finding ontologies:

"SIMILE is focused on developing robust, open source tools that empower users to access, manage, visualize and reuse digital assets. SIMILE seeks to enhance inter-operability among digital assets, schemata/vocabularies/ontologies, metadata, and services. A key challenge is that the collections which must inter-operate are often distributed across individual, community, and institutional stores. We seek to be able to provide end-user services by drawing upon the assets, schemata/vocabularies/ontologies, and metadata held in such stores. SIMILE will leverage and extend DSpace, enhancing its support for arbitrary schemata and metadata, primarily though the application of RDF and semantic web techniques. The project also aims to implement a digital asset dissemination architecture based upon web standards. The dissemination architecture will provide a mechanism to add useful "views" to a particular digital artifact (i.e. asset, schema, or metadata instance), and bind those views to consuming services. To guide the SIMILE effort we will focus on well-defined, real-world use cases in the libraries domain. Since parallel work is underway to deploy DSpace at a number of leading research libraries, we hope that such an approach will lead to a powerful deployment channel through which the utility and readiness of semantic web tools and techniques can be compellingly demonstrated in a visible and global community. The SIMILE Project and its members are fully committed to the open source principles of software distribution and open development and for this reason, it releases the created intellectual property (both software and reports) under a BSD-style license."

" The distinction between integration and interoperability is really a case study in architecture. The principle that any structural or software architect considers when building a framework is the separation of concerns into layers of responsibility. To keep autonomous systems discrete, the interoperability architect will focus on making the information and systems interoperable while avoiding a monolithic, tightly coupled integration effort. [...] The market is starting to open up to provide this next generation of capabilities. As we focus more on application interoperability, semantic transformation, and ontological mapping, business will benefit."